Attorney General Alberto R. Gonzales said yesterday that the government can obtain domestic telephone records without court approval under a 1979 Supreme Court ruling that authorized the collection of business records.

Gonzales would not confirm the details of a May 11 story in USA Today, which said the National Security Agency had collected phone records of millions of Americans and analyzed them to search for terrorism plots. But Gonzales told reporters that, under the Smith v. Maryland ruling, "those kinds of records do not enjoy Fourth Amendment protection. There is no reasonable expectation of privacy in those kinds of records."

The case involved the police, without a court warrant, asking a telephone company to install at its central office a surveillance device called a "pen register" that recorded all the numbers of a robbery suspect's outgoing calls.

Because the device was installed in a phone company's central office, the Supreme Court ruled that there was no invasion of the person's home. And because the telephone account owner knew, through a monthly bill, that the numbers dialed created a phone company record, there was no expectation of privacy and no violation of the Fourth Amendment that otherwise would have required a court warrant, the court said.

Gonzales has previously defended the government acquisition of phone company records on the grounds that privacy protections do not apply to them. But his reference to the 1979 Supreme Court case may hint that a technologically updated version of the pen register has been used on a much wider scale in the NSA operation.

At yesterday's news conference, Gonzales also appeared to soften a statement he made on Sunday about the possibility that a current investigation might lead to the prosecution of New York Times reporters who first disclosed the NSA's warrantless eavesdropping program.

"Let me try to reassure journalists that my primary focus, quite frankly, is on the leak -- on leakers who share the information with journalists," Gonzales said yesterday. He added that he would prefer to "try to persuade" journalists "that it would be better not to publish those kind of stories."